Dental articulator

ABSTRACT

Washer-like plates having transverse ridges for supporting the condyle ball and fossa on the lower and upper bars of a dental articulator cooperate with transverse groove-like serrations on the bars themselves to maintain precise positionings of the condyle and fossa mounts in vertical alignment. The condyle ball and fossa which supports an eminentia guide cam receiving the ball simulate the pivoting action of a person&#39;&#39;s jaw and therefore precise alignment is necessary. In addition, adjustments of the fossa can be effected without disturbing the horizontal position because of the cooperating ridges and groove-like serrations. In addition, the eminentia itself includes an extended lip portion of plastic material engaging the roof of the fossa to serve as a bearing for the condyle ball. This surface may be hollowed out or built up to provide very fine adjustments in the action of simulating the human joint of the jaw.

United States Patent [19] Stuart DENTAL ARTICULATOR [76] Inventor: Charles E. Stuart, Rancho Los Portules, 297 Kimball Rd., P.O. Box 1298, Ventura, Calif. 93100 [22] Filed: Mar. 16, 1973 [21] Appl. No.: 341,960

3,409,986 [1/1968 Freeman ..32/32 Primary ExaminerRobert Peshock Attorney, Agent, or Firm-Pastoriza & Kelly [11] 3,818,595 June 25, 1974 [5 7] ABSTRACT Washer-like plates having transverse ridges for supporting the condyle ball and fossa on the lower and upper bars of a dental articulator cooperate with transverse groove-like serrations on the bars themselves to maintain precise positionings of the condyle and fossa mounts in vertical alignment. The condyle ball and fossa which supports an eminentia guide cam receiving the ball simulate the pivoting action of a person s jaw and therefore precise alignment is necessary. In addition, adjustments of the fossa can be effected without disturbing the horizontal position because of the cooperating ridges and groove-like serrations. In addition, the eminentia itself includes an extended lip portion of plastic material engaging the roof of the fossa to serve as a bearing for the condyle ball. This surface may be hollowed out or built up to provide very fine adjustments in the action of simulating the human joint of the jaw.

5 Claims, 8 Drawing Figures r I I 1 DENTAL ARTICULATOR This invention relates generally to dental articulators and more particularly, to improvements in the coupling portions of the articulator, particularly the condyle ball and eminencia guide cam portions to enable more accurate simulation of a persons jaw movements.

BACKGROUND OF THE INVENTION Dental articulators are well known in the art and one of the better known and used articulators is that shown and described in my US. Pat. No. 2,816,360 issued Dec. 17, 1957.

As shown in my above mentioned patent and as is characteristic of other articulators in the prior art, the mountings for the condyle ball and fossa on lower and upper horizontal bars forming the joint or hinge axis for the articulating motion are slidable along the bars to adjust their separation distance. The adjustments of the condyle balls on the lower bar are independent of the adjustments of the fossae on the upper bar. In order that the condyle balls be received in the respective fossae, the fossae must be located directly above the condyle balls in vertical axial alignment therewith. Suitable markings or scales on the lower and upper bars facilitate this adjustment. Nevertheless, in attempting to visually align the condyle support and fossa support on the left and right sides of the lower and upper bars, errors can occur even with the use of a marked scale.

Further, in connection with the foregoing, once the proper spacing between the condyle balls and the fossae have been made, subsequent adjustments of each of the fossa which are universally mounted can upset the horizontal alignment adjustment since a single tightening nut is used for each fossa.

Finally, the eminentia supported by the fossa and as described in my above referred to patent, while interchangeable to provide different guide camming surfaces for the condyle balls, still present certain limitations in attempting to provide a guiding cam surface which will exactly simulate the human motions of the particular jaw under consideration. One of the problems is the fact that the top of the condyle ball engages the roof of the supporting fossa which constitutes a metal against metal bearing wherein no adjustment can really be made.

BRIEF DESCRIPTION OF THE PRESENT INVENTION With the foregoing in mind, it is a primary object of the present invention to provide an improved articulator over that shown in my above referred to prior patent wherein the problems associated with proper vertical alignment of the condyle balls and fossae are solved. In addition, the eminentia themselves are modified in a manner permitting a finer adjustment of the controlling cam surfaces to the end that more accurate simulation of jaw movement results.

Briefly, the improvements reside in the provision of lower and upper washer plates mounting the condyle ball and fossa respectively, the plates having transverse ridges and central guide blocks with threaded stems. The lower and upper bars of the articulator which. are slotted are provided in turn with transverse groove-like serrations at precisely spaced intervals formed on their top and bottom surfaces to define indexing marks for receiving the transverse ridges of the plates, the guide block portions of the plates being received in the slots of the bars. Tightening nuts in turn are threadedly received on the stem portions of the washer plate guide blocks for locking the plates in set positions.

Essentially, the horizontal positions of the condyle balls on the lower bar can be precisely matched by the fossae along the upper bar by positioning the mounting washer plates for the fossae on indexing marks corresponding to the indexing of the washer plates mounting the condyle balls, the transverse ridges on the washer plates fitting into corresponding grooves to assure precise indexing.

In addition to the foregoing, each eminentia guide can supported by a fossa comprises a plastic body having a lower rounded bottom portion and upper extending plastic lip portion co-extensive with the roof of the fossa to serve as a top bearing surface for the condyle ball, consistent seating of the ball on a given surface portion for a set position of the fossa in its universal mounting being assured as a consequence of the indexing of the ridges in the corresponding washer plate in the pre-selected grooves on the upper bar. This lip portion which may take the form of a plastic shim can be hollowed out or built up with plastic material to provide a properly contoured camming guide surface for the condyle ball so that very precise adjustments can be made for laterotrusion.

BRIEF DESCRIPTION OF THE DRAWINGS I ticulator incorporating the improvements of the present invention;

FIG. 2 is a side elevational view of the articulator of FIG. 1 in assembled relationship;

FIG. 3 is a greatly enlarged fragmentary exploded view of the condyle and fossa mounts in accord with the improvements of the present invention;

FIG. 4 is a fragmentary side view partly in cross section of the components of FIG. 3 in assembled relationship looking in the direction of the arrow 4;

FIG. 5 is a side cross section of the fossa and eminentia and cooperating condyle ball of FIG. 4;

FIG. 6 is a perspective view of a shim forming part of an eminentia;

FIG. 7 shows a plurality of various differently shaped modified eminentias in accord with the invention; and,

FIG. 8 is an end view in cross section illustrating how a portion of the eminentia can be hollowed out and built up to control its guiding cam surface.

DETAILED DESCRIPTION OF THE INVENTION Referring first to FIG. 1 there is shown a dental articulator similar in basic structure to the dental articulator shown and described in my prior referred to US. Pat. No. 2,816,360. Essentially, this articulator includes lower and upper T shaped frame structures, the cross left and right hand portions so that the upper T frame can be swung towards and away from the lower T frame when the parts are assembled to simulate the motions of a human jaw. These left and right hand coupling means take the form of left and right hand condyle balls 14 and 15 positioned on the lower bar 10 and left and right hand eminentia 16 and 17 supported in fossae l8 and 19 in turn universally coupled to the left and right hand portions of the upper bar 11.

Inner condyle balls 20 and 21 on the lower plate 10 in urn cooperate with guiding cam surfaces 22 and 23 mounted on the upper bar 11. The angulation of the planes of the surfaces 22 and 23 can be adjusted to guide movements of the upper bar 11 relative to the lower bar 10 during articulating motion.

The swinging axis or hinge joint axis for the articulator is defined turn the axis X-X in FIG. 1 which passes through the exact center of the condyle balls 14 and 15. As indicated by the double headed arrows adjacent to the condyle balls and adjacent to the fossae on the upper bar 11, these mountings may be independently slidable along the bars 10 and 11 respectively. In making adjustements, it is vitally important that once the condyle balls 14 and 15 have been adjusted a certain distance apart from each other along the bar 10 that the corresponding cooperating fossa on the bar 11 be correspondingly adjusted so that vertical alignment will be assured; that is, a consistent position of the condyle ball in its bearing engagement with the eminentia l6 and 17.

The improvements of the present invention are concerned with the relationship between the condyle ball supports and the fossa supports along the bars 10 and 11. The various other components and features as well as adjustments of the articulator are fully set forth and explained in my referred to prior patent.

FIG. 2 shows the T shaped frame structures of FIG. 1 in assembled relationship in side view wherein the upper bar 11 has been swung upwardly relatively to the lower bar 10 to simulate the opening movement of the human jaw. In FIG. 2, denture casts A and B are shown mounted on the stem portions 12 and 13 respectively of the T shaped structures.

In simulating the human jaw movements, it will be appreciated that more is involved than a simple hinging action about the X axis. In addition to the hinging or swinging motion, one jaw can move relatively to the other. For example, the human mandible can also move laterally or sideways as well as forwardly and rearwardly, these translational type motions being referred to as laterotrusion movements. It is therefore necessary that the joint" defined by each of the condyle balls and cooperating receiving eminentia be designed to simulate such laterotrusion movements.

Referring now to the enlarged fragmentary exploded view of FIG. 3, details of the condyle ball and fossa mountings relative to the bars 10 and 11 will be described.

Referring first to the lower bar 10 and the mounting for the condyle ball 14, it will be noted that this mounting includes a washer plate 24 having transverse ridges 25 and 26 in spaced parallel relationship. The central portion of the washer 24 includes a guide block 27. The top surface of the lower bar 10 in turn includes a series of transverse groove-like serrations 28 and 29 at precisely spaced intervals, the bar including an elongated central slot 30 as shown.

A threaded stem 31 extends from the central block 27 on the washer plate 24 and passes through the slot 30 when the parts are assembled, the ridges 25 and 26 being received in correspondingly positioned grooves 28 and 29. A tightening nut 32 is threadedly received on the lower end of the stem 31 to lock the washer plate 24 and thus the condyle ball in a given horizontal position along the bar 10. An indexing scale 33 corresponding to the serrations may be provided as shown on the bar 10 for cooperation with an indexing mark 34 on the washer plate 24.

Referring now to the upper bar 11 and the associated mounting for the fossa 18, this fossa 18 is universally mounted as by a yoke structure 35 having a yoke axis X-X for the fossa 18, the end of the yoke being carried in a support 36 for rotation about a second horizontal axis Z--Z orthogonal to the X--X axis. The support 36 in turn is rotationally mounted about a vertical axis YY to a washer plate 37 similar to the washer plate 24 for the condyle ball 14 but in an inverted positron.

The washer plate 37 includes transverse ridges 38 and 39 and a central guide block 40. The bar 11 in turn includes transverse groove-like serrations 41 and 42 and is provided with an elongated central slot 43. A threaded stem 44 connected to the guide block is received through the slot 43 so that the ridges 38 and 39 seat in selected ones of the serrations 41 and 42 when the mounting is assembled. A tightening nut 45 is provided to thread on the end of the stem 44 on the top portion of the upper bar 11. As in the case of the lower bar 10, there is provided a corresponding scale 46 for the serrations 41 and the washer plate 37 in turn is provided with an indexing mark 47.

Referring now to the assembled side view of FIG. 4, it will be evident that the two orthogonal horizontal axes X--X and Z--Z together with the vertical axis YY all pass through the exact center of the condyle ball 14 when the same is received in the eminentia guide cam held by the fossa 18. It will also be noted that the washer plates 10 and 11 have their respective ridges seated in selected grooves of the lower and upper bars 10 and 11 so that they are in precise vertical alignment.

Referring now to the fragmentary cross section of FIG. 5, it will be noted that the eminentia shown is slightly different from that in my heretofore referred to US. patent. More particularly, the eminentia 16 includes a lower rounded body portion 16a and an extending upper lip plastic portion 16b substantially coextensive with the roof of the fossa 18. This extended lip portion defines a top bearing surface for the condyle ball 14 as at 48, the rounded lower portion 16a providing a tangential hearing as at 49.

The eminentia 16 itself is removably supported in the fossa 18 as by a small screw 50.

Referring now to FIG. 6, there is shown a plastic shim 51 which may be provided with small center end slots 52 and 53. This shim may be utilized with the old type of eminentia which is not provided with the extending lip portion 16b as described in FIG. 5. ln otherwords, by simply positioning this shim beneath the roof of the fossa and the old type eminentia, a top bearing surface for the condyle ball 14 can be provided. The small slots 52 and 53 will accomodate the holding screw 50 regardless of the manner in which the shim 51 is inserted between the eminentia and the roof of the fossa l8.

FIG. 7 shows the new modified type of eminentia wherein the lower curved portion may assume different shapes or forms as indicated at 16a, 16a and 16a. Any one of the eminentia shown in FIG. 7 can be substituted in the fossa 18 described in the other figures to thereby provide a different contoured camming surface for the condyle ball 14 and thus permit accurate adjustment of sliding movement of the eminentia on the condyle ball 14 when simulating sliding type laterotrusion movements of the jaw.

Further refinement in the adjustment of the eminentia can be effected by hollowing out or building up surface portions of the plastic shim or lip portion of the eminentia itself. Thus, referring to FIG. 8 there is shown in end view a shim 54 which would constitute an integral lip portion of the modified type of eminentia wherein the underside is provided with a hollowed out portion 55 and a build up portion 56 for providing a guiding cam surface for the condyle ball 14. Riding of this guiding cam surface portion of the eminentia on the condyle ball results in movement of the upper T frame structure of the articulator in a manner properly simulating the jaw movement of the human jaw.

It will be understood that the desired adjustments are effected by following traces provided on a recorder such as shown and described in my US. Pat. No. 2,814,876 issued Dec. 3, 1957.

OPERATION The overall operation of the dental articulator is fully set forth in my referred to prior US. Pat. No. 2,816,360. With respect to the improvements of the present invention, it will be appreciated that adjustment of the horizontal positions along the bars of the condyle ball mountings and the fossa mountings are greatly facilitated as a consequence of the cooperating ridges and groove-like serrations. Thus, once the condyle balls are set as by seating of the washer plate ridges in selected groove-like serrations in accord with the scales on the lower bar 10, the upper mountings may be precisely positioned vertically above the condyle ball 14 by selecting the proper corresponding serrations for seating of the grooves on the washer plates associated with the fossa supports. In otherwords, a consistent positioning of the condyle ball 14 on the camming guide surface of the eminentia is assured provided that the mountings for the condyle ball and fossa supporting the eminentia are consistent. Such consistent positioning is greatly facilitated and assured by the cooperating ridges and serrations.

An advantage of the foregoing structure resides in the fact that rotational movement of the fossa about the vertical YY axis can take place without upseting the horizontal positioning of the fossa mounting along the bar 11. Thus with specific reference to FIG. 4, it will be appreciated that the tightening nut 45 can be loosened slightly to permit rotation of the support 36 about the YY axis relative to the washer plate 37. The washer plate 37 will not rotate or move because of the engagement of its ridges within the serrations on the underside of the bar 11, provided the nut 45 is not loosened too much. Thus the various adjustments of the universal mounting for the fossa 18 can very easily be carried out as compared to such adjustments made heretofore wherein the positive locking provided by cooperating ridges and serrations was lacking.

Finally, as a consequence of the provision of the extended lip on the eminentia or the provision of shims as the case may be there is provided a plastic top bearing for the condyle ball which may be formed to provide for accurate guiding in accord with recording tracings on a suitable recorder so that more accurate simulation of all jaw movements can be efiected in the articulator.

While the eminentia, lip portion, and shims have been described as plastic, they may, of course, be formed of any other material which can be suitably contoured to provide for proper movements of the articulator.

What is claimed is:

I. In a dental articulator including lower and upper T shaped frame structures, the stems of the Ts serving to support lower and upper denture casts respectively and the cross portions of the Ts including lower and upper spaced parallel slotted bars; and left and right articulating coupling means mounted in the slots of the bars between the left and right hand portions thereof simulating the human condyle joints of the jaw so that the upper T frame can be swung towards and away from the lower T frame to close and open the denture casts when mounted on the stems of the TS in a manner following the same motions as a persons jaw, the distance between the left and right coupling means being adjustable by moving the coupling means towards and away from each other along the slots of the bars, and wherein each articulating coupling means includes a condyle ball mounted in the slot of the lower bar and a fossa supporting an eminentia guide cam receiving the ball mounted in the slot of the upper bar, the improvement comprising:

a. lower and upper washer plates mounting the condyle ball and fossa, having transverse ridges and central guide blocks with threaded stems; and,

b. a series of transverse groove-like serrations at precisely spaced intervals formed on the top and bottom surfaces of the lower and upper bars defining indexing marks for receiving said transverse ridges of the plates when the guide blocks and stems on the plates are received in the lower and upper bar slots respectively; and

c. tightening nuts threadedly receivable on the ends of the stems passing through the slots so that the washer plates mounting the fossae can be locked in set positions whereby the exact horizontal positioning of the condyle balls on the lower bar can be precisely matched by the fossae along the upepr bar by positioning the mounting washer plates for the fossae on indexing marks corresponding to the indexing marks for the washer plates mounting the condyle balls, the transverse ridges on the washer plates fitting into corresponding grooves to assure precise indexing.

2. The improvement of claim 1, in which each fossa supporting and eminentia guide cam is universally mounted for individual rotation about either of two orthogonal horizontal axes and one vertical axis, all passing through the center of the cooperating condyle ball, rotation of the fossa about the vertical axis being effected by rotational sliding movement on the washer plate, the ridges on the plate holding the blade against horizontal and rotational movement so that the exact horizontal position of the fossa along the upper bar is not lost when loosening the tightening nut for purposes of rotational adjustment of the fossa about said vertical axis for laterotrusion.

3. The improvement of claim 2, in which each eminentia guide cams supported by a fossa comprises a body having a lower rounded body portion and upper extending lip portion coextensive with the roof of the fossa to serve as a top bearing surface for the condyle ball, consistent seating of the ball on a given surface portion for a set position of the fossa in its universal mounting being assured as a consequence of the indexing of the ridges in the corresponding washer plate in the preselected grooves on the upper bar.

4. The improvement of claim 3, in which said extend- 8 ing lip portion is provided by a shim positioned between the rounded body portion and the roof of the fossa, the shim extending beyond the upper end of the rounded body portion.

5. The improvement of claim 4, wherein there are provided a plurality of eminentia of different lower rounded body shapes for substitution in the supporting fossa so that adjustments of the shape of the guide cam surface for the condyle ball can be made, the portion of the eminentia lip portion or shim being such that further fine adjustments can be made for laterotrusion by hollowing out and building up portions of the shim. 

1. In a dental articulator including lower and upper T shaped frame structures, the stems of the T''s serving to support lower and upper denture casts respectively and the cross portions of the T''s including lower and upper spaced parallel slotted bars; and left and right articulating coupling means mounted in the slots of the bars between the left and right hand portions thereof simulating the human condyle joints of the jaw so that the upper T frame can be swung towards and away from the lower T frame to close and open the denture casts when mounted on the stems of the T''s in a manner following the same motions as a person''s jaw, the distance between the left and right coupling means being adjustable by moving the coupling means towards and away from each other along the slots of the bars, and wherein each articulating coupling means includes a condyle ball mounted in the slot of the lower bar and a fossa supporting an eminentia guide cam receiving the ball mounted in the slot of the upper bar, the improvement comprising: a. lower and upper washer plates mounting the condyle ball and fossa, having transverse ridges and central gUide blocks with threaded stems; and, b. a series of transverse groove-like serrations at precisely spaced intervals formed on the top and bottom surfaces of the lower and upper bars defining indexing marks for receiving said transverse ridges of the plates when the guide blocks and stems on the plates are received in the lower and upper bar slots respectively; and c. tightening nuts threadedly receivable on the ends of the stems passing through the slots so that the washer plates mounting the fossae can be locked in set positions whereby the exact horizontal positioning of the condyle balls on the lower bar can be precisely matched by the fossae along the upepr bar by positioning the mounting washer plates for the fossae on indexing marks corresponding to the indexing marks for the washer plates mounting the condyle balls, the transverse ridges on the washer plates fitting into corresponding grooves to assure precise indexing.
 2. The improvement of claim 1, in which each fossa supporting and eminentia guide cam is universally mounted for individual rotation about either of two orthogonal horizontal axes and one vertical axis, all passing through the center of the cooperating condyle ball, rotation of the fossa about the vertical axis being effected by rotational sliding movement on the washer plate, the ridges on the plate holding the blade against horizontal and rotational movement so that the exact horizontal position of the fossa along the upper bar is not lost when loosening the tightening nut for purposes of rotational adjustment of the fossa about said vertical axis for laterotrusion.
 3. The improvement of claim 2, in which each eminentia guide cams supported by a fossa comprises a body having a lower rounded body portion and upper extending lip portion coextensive with the roof of the fossa to serve as a top bearing surface for the condyle ball, consistent seating of the ball on a given surface portion for a set position of the fossa in its universal mounting being assured as a consequence of the indexing of the ridges in the corresponding washer plate in the preselected grooves on the upper bar.
 4. The improvement of claim 3, in which said extending lip portion is provided by a shim positioned between the rounded body portion and the roof of the fossa, the shim extending beyond the upper end of the rounded body portion.
 5. The improvement of claim 4, wherein there are provided a plurality of eminentia of different lower rounded body shapes for substitution in the supporting fossa so that adjustments of the shape of the guide cam surface for the condyle ball can be made, the portion of the eminentia lip portion or shim being such that further fine adjustments can be made for laterotrusion by hollowing out and building up portions of the shim. 